Semimechanical telephone system



-A. M. BULLARD. SEMIMECHANICAL TELEPHONE SYSTE M. APPLICATION FILED FEB. 5. I907- RENEWED NOV- 3, 1909.

Patentd Mar. 16, 1920.

- omrun STATES PATENT OFFICE.

ALBERT M. QBULLABD, F .NEW.YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO WESTERN ELECTRIC COMPANY INGOR-PORATED, A'CORPORATIION OF NEW YORK.

'SEIVITMECHAN'IGA L TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Mar. 1c, 1920'.

. lpplication fled February 5, 1907, Seria1 130,855,897. Renewed November 8, 1909. YSeTia-INc. 526,890.

To all whom it may concern:

Be it known that I. ALBERT M. BULLARD, citizenof the United States, residing .at New York, inithe county of New York and State of New York, have invented a certain new and useful Improvement :in Semi-mechanical Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates-to improved revertivecallindicating means for telephone exchangesystems having party lines. In such a System it frequently occurs that a :subscriber at one of the substations of party linedesires to connuunicate with a subscriber at another station of the same line. The ordinary busy test in such a. case will give a false busy indication because a test guard has been placed upon the multiple terminal of the line, by reason of the use of that line in calling and not because it is already engaged by some other subscriber. It is not desirable, however, that under ordinary traflic conditions either :the calling subscriber or the operator should be required to, know from the mere number of the called station whether it is on the same party line as the calling station. 7

It is the purpose, therefore, of this invention to provide improved means for giving a special signal in all cases of such revertive calls. that is, where the terminal of the called line which is tested, is merely a multiple terminal of the calling line. A signal device is associated with the originating or answering end of the connecting circuit which is united with any calling line in rc-' spouse to a call, and onetcrminal of said signaling device is arranged to be connector thereby to a conductor of the calling line which extends to contacts at all of the multiple terminals of such line. Switching apparatus associated with the other end of the connecting circuit adapted to connect the other terminal of said signal device to a multiple terminal of a. conductor c rre sponding to the conductor to which the signal device is connected at the originating or answering end of the connecting circuit. so that where the terminal with which contact is made is a multiple terminal of the calling line, the circuitof said signal device will be completed and the signal given to indicate that the call is a revertive one.

l7referably the special signal apparatus brought into operative relation with the connecting "circuit and the signal device connected to a conductor of the calling line only 'momentarily at the time when the switching apparatus is testing the terminal ofthe called line at this :same time the usual test guard upon the. test conductor of the calling line may be removed, such test uard being ot erwise maintained at all .miilti-ple terminals of the line during the entire period of connection therewith.

This invention will boot especial utility in connection with semi-automatic systems of the type in which the calls are answered by an operator and connection completed to the called line by meansof automatic switching mechanism controlled by the operator, as shown .for example in Patent 1,161,608 of November 23, 19.15, to A. M. .Bullard.

The invention is illustrated by the accompanying drawing in its application to such a system. Only the circuits and apparatus which are directly concerned with the invention are illustrated, however.

In the drawings, .1, 2 and 3 represent respectively the tip, ring and sleeve of an operators answering plug, while 4, 5 and 6 show thc'corresponding answering jack terminals of a subscribers line 7. This subsc'ribers line'7 is a party telephone line of usual construction andarrangement, comprising conductors 8 and Y91, having connected 'therewiththrough the contacts of the usual cut-off relay 10 associated therewith the usual line relay 11 and source of current 12. One terminal of the cut-off relay 10 is connected, as is customary, with the test conductor and the sleeve contact individual to the line. 37, and the other terminal oi such cut-off relay is connected, as is also usual, to the grounded battery 13. The line 7 provided also with multiple contacts 1%, 15 and 16, connected, respectively, by the conductors '1 7,'18 and 119 tothe tip, ringand sleeve contacts 4;, '5 and 6 of the answering ack of such line. These multiple contacts, of which only one set are shown, are .indicatedupon the right hand side of the drawing, but it will be understood that there maybe as many sets of these multiple contacts as maybe desir-able. o

WVhen a subscriber upon the line 7, which, as above noted, is assumed to "be a party telephone line, desires connection with an- 4 The operator thereupon inserts the plug 20 in the jack 21 in order to receive a call. Immediately upon the insertion of this plug, which has brought the tip, ring and sleeve contacts 1,2 and 3, respectively, into contact with the corresponding contacts 4, 5 and 6, respectively, a test guard is placed upon the test conductor 19 of the calling line by means of a low resistance circuit to ground, extending from the sleeve contact 6 of the answering jack 21, through the sleeve 3 of the plug 20, conductor 22, conductor 23, back contact and armature 24 of the relay 25, to be hereinafter referred to, conductor 26, sleeve relay 27 to ground; This providesa path for current from the battery 13, which operate the cut-oil relay 10 and the sleeve relay 27 in the usual manner and lowers the normal potential upon the sleeve or test contact 6 of the answering jack and. also upon the test contact 16 of the multiple contacts. it may here be noted that a circuit to maintain the sleeve relay 27 energized after its initial energization, is providedin parallel of the armature 24 and its back contact through the high resistance 28, which circuit, however, when the armature 24 has been attracted by the relay 25 and has opened shunt around the high resistance 28, is of too high resistance to sufliciently lower the potential of the'sleeve or test contact 6 and the connected multiple test contacts 16 to make such contacts test busy.

The operator having learned from the calling subscriber the number of the desired party causes the automatic switching device 29 shown in detail in Fig. 4 of said patent, at which the multiple contacts l4, 15, 16 appear, to bring its contact brushes 30, 31, 32 by means of a sender such, for example, as that shown in Figs. 5, (Sand 7 of said patent, into contact with the multiple terminals 14, 15, 16 of the line on which the desired party is located. lVhen this automatic switching device has made its final selective movement and the contact brushes 30, 31, 32

ar in contact with the multiple terminals 14, 15, 16 of the desired line, the switch 33 is arrangedto be operated automatically the instant the connector reaches the terminals of the desired line. This contact 33 corresponds to the armature 32 and front contact of relay 33 of Fig. 5 of said patent. The relay 33 is operated automatically by the sender at the termination of units selection. This partoi' the operation of the system of said patent is described in detail on page 15, lines to 82 inclusive and page 22, lines 7 to 52 inclusive. I

Theenergization of the relay 25, which corresponds to relay 491 of said patent, due to the closure of the circuit through the switch 3 will attract its various armatures. The attraction of the armature 24 will open the shunt around the high resistance 28 and in so doing will remove the test guard from the sleeve contact 6 of the jack 21 and from the associated multiple contacts 16, so that the automatic switching device 29 in testing 'the line will find it unguarded and apparently in idle condition, the circuit through the highresistance 28 and the sleeve relay 27 being, as has been before noted, of too high resistance to reduce appreciablythe potential of the sleeve contact 6 from its normal or idle potential, due to the connection of the battery 13. Suflicient current, howeve will continue to pass from the battery 13 through the cut-0E relay 10 and the sleeve relay 27 to maintain the sleeve relay 27 energized. The attraction of the armatures 35 and 36 has opened at their back contacts the normal groundconnections of the tip conductors 37 and 38 of the connecting circuit and at the same time has through their front contacts included in the circuit of the tip conductors 37 and 38, a source of current 39 and a winding 40 of the relay 41. This source of current 39 may be of any de:

sired character, but is preferably, as shown,

the secondary winding of an induction coil 42, the primary winding 43 of which is in circuit with the constantly operating source of pulsating or alternating current 44.

Assuming now that at the time therelay is energized, the brushes 30, 31 and 32 of the automatic switching device. 29 are in 7 contact with the multiple terminals of the calling line, that is, the line with which the plug 20 is connected'through the jack 21, a circuitwill be established from the source of alternating current 39 through the armature 36 and its front contact, conductor 45, tip conductor "37 of the originating end of the connecting circuit, tip contact 1 of the plug 20, corresponding contact 4 of the jack 21, conductor 17, multiple contact 14, brush of the automatic switching device 29, tip conductor 38 of the connecting circuit, conductor 46, armature and its front contact, conductor 47 winding of the relay 41, and back to the source of alternating current 39. This will cause the energize.- tion of the relay 41, which will attract its armatures, and in so doing will establish for itself a locking circuit from the battery 48, armature 49 and its front contact of the relay 27, which relay, it will be remembered, remains energized by current from. the bat tery 13, conductor 50, conductor 51, armature 52 and its front contact, winding 53 ot' the relay 41 and ground. back to battery. The attrartion of the armature 54 by the relay 41 has opened the normally closed connection through the armature 54 and its back contact of the ring conductor 55 of the connecting circuit, and has closed a circuit from the battery 56 through the supervisory relay 57, ring conductor 55, armature 54 and its front contact, conductor 58, pulsator 59 to ground and back to battery. The making and breaking of this circuit by the pulsator 59 will cause the corresponding encrgization and deen'er'gization of the supervisory relay 57 which will in turn cause a corresponding flashing of the supervisory lamp 60. 'The current for this lamp is supplied from battery as through the armature 4:9 and its front contact of the relay 27, conductor 50, armature 61 and its back contact of the supervisory relay 57, supervisory lamp 60 and thence to ground and back to battery. The relay 41 having once been energized by the momentary closure of the circuit through the Winding 40 will remain locked in energized condition by current through the winding 53 so long as the relay 2? is energized. It will therefore be seen that if the call over the line 7 is a revertive one, the momentary energization of the relay 25 will, in the first place, remove the test guard from the multiple contact 16 of the calling line, in order that the automatic switching apparatus will not find a test guard upon the terminal 16, and, in the second place, will cause a distinctive signal to be displayed before the operator, which distinctive signal will continue until the operator removes the plug from the jack 2i. and thereby opens the intermittently closed circuit through the pulsat'or and the supervisory relay 57. The distinctive signal referred to is obviously the intermittent flashing of the supervisory lamp which has been hereinbefore described.

The operator, having had brought to her attention the fact that the call is a revertive one, ,may proceed in any suitable way and any suitable means to ring the desired party upon the calling line 7 but since this forms no part of the present invention, no

means for accomplishing this result need be shown, the only necessary act to accomplish the restoration of the apparatus to iormal, so far as relates to this invention, icing the lfzlEiOVzll. of the plug 20 from the jack '21 in order to dee'nergize the relays 27 and 41, which removal will necessarily occur in the ordinary operation of asystem of this character and or after the ringing of the desired party.

If, however, at the tiinethat the switch 33 is momentarily closed, as before de scribed, the brushes 30, 31, 32 of the automatic switching apparatus were in connection with the multiple test terminals of line other than the calling line, the circuit from the source of alternating current including the winding 40 of the relay 41 and the armatures and 36 and their frcnt contac-ts of the relay will not be completed since the brush 30 of the automatic switching apparatus 29 is not in contact with the multiple terminal. of the calling line, and no ci-rcuitwill therefore be may be either before established from the tip contact 1 of the plug 20 through the corresponding contact 4: of the j'ack21, conductor 17 and the multiple contact 1a of the cal-lingiline to the brush 30. The relay 41 will therefore re? main unenergized and theflashing of the supervisory lamp 60, as above described, will not occur. The operator therefore will know that'the call is not 'a revertive one and will not pe'rform'any special acts in connection therewith, but will allow connection to be established in the way usual to such systems. 1

It may here be noted that during the establishment of each connection, the test guard is momentarily removed from the calling line, whether or no thecall be a revertive one, but such removal of the test guard bein -only momentary, will not detrimentally "aifect the proper operation of the system."

The connecting circuit, which is only -dia grammatically shown, since it in itself forms no part of this invention, comprises, as is usual,-in addition to the parts already described, a supervisory relay 62 included in the ring conductor 63 of the originating "or answering end of the connecting circuit and the usual repeating coil windings 64, 65, 66 and 67, inserted, respectively, in the conductors '37, 38, 63 and 55. The automatic switching device 29 and its associated test circuit '68 and test relay 69 are shown only so far as they are necessary for a fulland definite understanding of this invention, and it will of course be understood that they may be of any ordinary or usual construction that may be desired.

It will therefore be seen that in the operation of a system involving this invention,

it the call is arevertive one, the automatic switching apparatus will be allowed to seize the calling line atits multiple contacts in such switching apparatus in spite of the normal application of the test guard at the originating end of the connecting circuit, and furthermore that a distinctive signal will be displayed indicating that the call is a revertive one. On the other hand, if the call is not a revertive call, the ordinary or normal operation of the system is in no way interfered with or changed, and no unnecessary burden is at anytime placed upon the operator or upon thetcalling subscriberin order to accomplish the proper connection in a revertive call. Y i

It should be understood that in all cases where the originating end of-the connecting circuit is referred to, either in the specification or claims, that-end of the connecting circuit is meant which corresponds to the answering end of an'operators cord circuit in a manual system, whether such connecting circuit the means for interconnectautomatic or manual system. It should be further understood that while this invention is shown as applied to a semi-automatic telephone exchange system and is of especial utility in connection with such a system, it is also well adapted for use either in connection with a full automatic telephone exchange system, or a manual telephone exchange system, and it is not to be considered as limited to a semi-automatic system any further than the claims hereinafter appended may indicate.

It should be further understood that while there are shown various and independent batteries in connection with the disclosure of the invention, where these batteries are of the same polarity and potential, and are located in the same exchange,-they may be and preferably are one and the same battery.

Having described my invention what I claim and desire to secure by Letters Patent 7 of the United States is:

1. In a telephone exchange system, the combination with a party telephone line having multiple terminals, of a connecting circuit. adapted to be united therewith, a revertive signal, a controlling relay therefor, associated with the originating end of said connecting circuit, and an operative circuit for said relay completed only through multiple terminals of said party line, at each end of said connecting circuit. 7

2. In a telephone exchange system, the

combination with a party telephone line having multiple terminals, of a connecting circuit adapted to be connected therewith, a revertive signal, a controlling relay therefor,'associated with the originating end of said connecting circuit, and an operative circuit for said relay completed only through a talking conductor and multiple terminals of said party line at each end of saidconnecting circuit. 7

In a telephone exchange system, the

combination with a party telephone line having multiple terminals, of a connecting circuit adapted to be united therewith, a signal device associated with said connecting circuit, and a circuit for said device including corresponding terminals of said connecting circuit at each end thereof and mul tiple terminals of said party line.

4. In a telephone exchange system, the combination with a party telephone line having multiple terminals, of a connecting circuit adapted to be united therewith, a signal device associatedwith said connecting circuit, and a circuit for said device including corresponding terminals of said connecting circuit at each end thereof and multiple terminals of said party line.

5. In a telephone exchange system, the combination with a party telephone line having multiple terminals, of a connecting circuit adapted to. be united therewith, a

revertive signal device, a relay controlling the same associated with the originating end of said connecting circuit, an operative circuit for said relay completed only through multiple terminals of said party line at each end of said connecting circuit, and a switch in said connecting circuit momentarily operated to close the circuit of said relay, whereby said relay will be operated by the closure of said switch only when said connecting circuit is connected at both ends to the same line.

6. In a telephone exchange system, the combination with a party telephone line having multiple terminals, of a connecting circuitadapted to be united with said termi nals, a revertive signal, a controlling relay therefor, associated with the originating end of said connecting circuit, a circuit for said relay including a talking conductor and multiple terminals of said party line at each end of said connecting circuit, and a switch in said connecting circuit momentarily operated to close the circuit of said relay, whereby said relay will be operated by the closure of said switch only when said connecting circu t 1s connected at both ends with the same hne.

7. In a telephone exchange system, the

combination with a party telephone line having multiple terminals, of a connecting circuit adapted to be united therewith, a signal device, a circuit for said signal device including said multiple terminals of party line and corresponding terminals of said connecting circuit at each end thereof, and a switch in said circuit momentarily operated to close a circuit of said signal device, whereby said signal device will be operated by the closure of said switch when said connecting circuit is connected at both ends to the same line; i

' 8. In a telephone exchange system, the combination with a party telephone line, a connecting circuit, means for uniting said connecting circuit with said-partyline, automatic switching apparatus adapted to unite said connecting circuit with a called telephone line, and a revertive call indicat ing signal automatically operated when said switching mechanism makes connections with the calling line.

9. In a telephone exchange system, the

combination with a party telephone line, of

a connecting circuit, a connection switch.

for uniting said'connecting circuit to said line'in response .to a call, automatic switching apparatus for uniting said connecting circuit with other lines and a revertive call indicating signal automatically operated when said automatic switching apparatus unites with the calling line in response to a call therefor. 1

10. In a telephone exchange system, the combination with a party telephone line having multiple terminals, of'a connecting terminating in air automatic switching device, one of said multiple terminals being located in said switching device, a signal device, a circuit for said signal device including contacts of-said multiple terminals at both ends of said connecting circuit, and a switch for closing the circuit of said signal device, whereby said signal device will be operated by the, closure' ot said switch when said automatic switching device is connected to a multiple terminal of the same line to which said connecting circuit is united at its originating end.

'11. In a. telephone exchange system, the combination with a party telephone line having multiple terminals, of a connecting circuit adapted to be imited therewith terminating in an automatic switching device, one. of said multiple terminals being located in said switching device, a signal device and a circuit for said signal device including contacts of said multiple terminals at both ends of said connecting circuit, and a switch for closing the circuit of said signal device, whereby said signal device will be operated upon the closure of said switch when said connecting circuit is in contact at both ends with the multiple terminals of the same line.

12. In a telephone exchange system, the combination with a party telephone line having multiple terminals, of a connecting circuit adapted to be united therewith terminating in an automatic switching device, one of said multiple terminals being located in said switching device, a signal device, a circuit for said signal device ir" eluding a talking conductor and contacts of said multiple terminals at both ends of said connecting circuit, and a switch for closing the circuit of said signal device, whereby said signal device will be operated upon the closure of saidswitch-when said connecting circuit. is in contact at. both ends with the multiple terminals of the same line. 7

13. In a telephone exchange system, the combination with a party telephone line having multiple terminals, some of said terminals being located upon automatic switching devices, an answering switch adapted to make contact with said line when calling, a signal device adapted to be associated with said calling line, an automatic switching device to which connection may be extended from said line, through said answering switch, said switching device havin access to one of the multiple tern'iinals or said line, and a circuit for said signal device including contacts of said answering switch and multiple contacts of said party line in-said'automatic switching device adapted to be completedwhen said automatic switching device is in contact with the multiple terminals of the calling line. I

'14:, In telephone exchange system, the

combination with a party telephone line, a

connecting circuit, a connecting switch for uniting said connecting circuit with said line, automatic switching apparatus for uniting said connecting circuit with other lines, a supervisory signal associated with said connecting circuit, and means automatically actuated when said switching mechanism selects the calling line in response to a call for causing said supervisory signal to give a characteristic revertive call signal.

15. In a telephone exchange system, the combination with a party telephone line, of a connecting circuit, 7 a manually operated connecting switch. for uniting said connect ing circuit with said line, automatic switching apparatus adapted to unite said connecting circuit with a desired line, a relay, acircuit for operating said relay adapted to be completed as the automatic switching ap paratus is testing a called line, a supervisory signal associated with said connecting circuit, and meanscontrolled by said re in the test of the calling line in response to a call therefor to cause said supervisory signal to give a characteristic call signal.

16. In a telephone exchange system, the combination with a party telephone line, of a connectingcircuit, a manually operated connecting switch for uniting said connecting circuit with said line, automatic switching apparatus adapted to unite said con.- necting circuit with other lines, a relay 25, a circuit therefor adapted to be completed while such automaticv switching apparatus is testing the called line, a relay all, a re vertive call signal operated by said relay 41 when energized, and a circuit to operate said relay ill completed by relay 25 when said automatic switching apparatus makes connection with the calling line.

17. In a telephone exchange system, the combination with a party telephone line, of a connecting circuit, a manually operated connect-ing switch for uniting said connecting circuit with a calling line, automatic switching apparatus adapted ;to unite said connecting circuit with the desired line, a relay 25, a circuit for operating same adapted to be completed as the automaticswitching apparatustests a called line, a relay ll, a revertive call signal actuated by said relay when energized, and a circuit to operate said relay closed by said relay 25 when energized through the terminals of the calling line associated with said automatic switchin ap- I: A

paratus and the manuallyoperated connection switch when said automatic s "itching apparatus makes connection with thecalling line in response to. a, call.

l8, Ina telephone'ex'change system, the

combination with a paity telephone line, of a connectino circuit adapted to unite said line with other telephone lines, a signal controlling device, means, automatically operated only upon the connecting of said 0011- necting circuit or" said party line with itself in response to a call from station on such line for any station on such line, to serially include said signal controlling device in said connecting circuit, and an operative circuit for said signal controlling device formed by said connecting circuit and calling line;

19. In a telephone exchange system, the combination with a party telephone line, of a connecting circuit, means for uniting one end of said connectinocircuit with said line in response to a cal, automatic switching apparatus for uniting the other end of said connecting circuit withtelephone lines, a signal controlling device, means automatically operated upon the connection of said switching apparatus with the calling line in response to a call from a substation on said line for another substation on said line, for including said signal controlling device serially in said connecting circuit, and an operative circuit for said signal controlling device formed by said connecting circuit, switching apparatus and calling line.

20. In a telephone exchange system, the combination with a party telephone line, of a connecting circuit adapted to be united with said line, automatic switching apparatus adapted to unitesaid connecting circuit with telephone lines in response to calls from said first mentioned line, a signal controlling device, means, automatically operated when said switching apparatus unites with a callino line for including said signal controlling cevice in the connecting circuit, and an operative circuit for said device completed when the switching apparatus unites with the calling line.

21. In a telephone exchange system, the combination with a party telephone line, of a connecting circuit, a connection switch "for uniting said connecting circuit with said. line, automatic switching apparatus adapted to unite said connecting circuit with telephone lines, a signal controlling device. means, operated upon the connectionof said switching apparatus with said'calling .line in response to a call from such line, for including said signal controlling device se-- rially in the connecting circuit, and an operative circuit for said device formed by said connecting circuit, switching apparatus, calling line and connection switch. 7

In a telephone exchange system, the combination with a party telephone line,jo't a connecting circuit adapted to be united with said line, automatic switching apparatus adapted to unite said connecting circuit with telephone lines, signal co t ling device and a source of current for operating the same, means, automatically operated when said switching apparatus unites with said calling line in response to a call therefrom, for including said signal controlling device and source of current in said circuit, and a circuit for said device and source formed by said connecting circuit, switching apparatus and calling line.

23. In a telephone exchange system, the combination with aparty telephone line, oi a connecting circuit adapted to be connected with said line, automatic switching apparatus adapted to connect said connecting cir cuit with telephone lines, said switching apparatus having a terminal connected with said calling line, a signal controlling device, means, automatically operated when said switching apparatus unites said connecting circuit with said calling line terminal in response to a call from such line, adapted to include said signal controlling. device serially in said connecting circuit, and an o'p-' crating circuit for said device formed by said connecting circuit, automaticswitching apparatus, calling line terminal and calling line.

24. I11 a telephone exchange system, the combination with a party telephone line, oi? a connecting cirouioadapted to be'connectcd with said line, automatic switching apparatus adapted to connect said connecting circuit with telephone lines said switching apparatus having a terminalconnected with 7 said calling line, a signal controlling device. a source of current, a conductor including said signal controlling device and source, means, automatically operated when said switching apparatus unites said connecting circuit with said calling line terminal in sponse to a call from such line, adapted to connect said conductor in series with said connecting circuit, and a circuit tors-aid sig nal controlling device formed by said conductor, connecting circuit, switching apparatus, calling line terminal and calling line.

25. In a telephone exchange system, the combination with a party telephone line, of a connecting circuit adapted to be connected with said line, automatic switching apparatus adapted to connect said connecting circuit with telephone lines, said switching apparatus having a terminal connected. with said calling line, a signal controlling device and a source of current, loop conductor including said device and source, a relay adapted when energized to connect said loop conductor with said connecting circuit, a circuit for said relay automatically completed when said switching apparatus connects sa d connecting clrcuit with the terminal of the calling line in response to a callrfrom such line, and a circuit for said ig; Lil controlling device completed by way oi: said loop conductor, connecting circuit, switching apparatus, callingline terminal and calling line.

26. In a telephone exchange system, the combination with. a party telephone line, of a connecting circuit adapted to be connected with said line, automatic switching apparatus adapted to connect said connecting circuit with telephone lines, said switching appa atus having a terminal connected with the calling line, aloop conductor having a signal controlling d rice and a source of al-.

combination with a party telephone line, of

a connecting circuit, a connection switch for uniting said connecting circuit with said line, automatic switching apparatus adapted to connect said connecting circuit with telephone lines, a loop conductor having a source of current and a relay included therein, a relay adapted to connectsaid loop conductor with said connecting circuit, a circuit for said relay adapted to be completed when the switching apparatus unites with the calling line in response to a call from such line, a circuit for said first mentioned relay and its operating current completed by way of said loop conductor, connecting circuit, switching apparatus, calling line and connection switch, and a revertive call signal device controlled by said first mentioned relay.

28'. In a telephone exchange system, the combination with a party telephone line, of a connecting circuit, a connection switch for uniting said connecting circuit with said line, switching apparatus adapted to connect said connecting circuitwith telephone lines, a loop conductor having a source of current and a relay included therein,'means, operated when said switching apparatus unites with the calling line in response to a. call from such line, for connecting said loop conductor with said connecting circuit to complete an operating circuit for said relay, a supervisory signal associated with said connecting circuit, and means controlled by said relay for causing said supervisory signal to give a characteristic indication.

29. In a telephone exchange system, the

I combination witha party-telephone line, of 'a connecting circuit, a connection switch for uniting said connecting circuit with said line, automatic switching apparatus adapted to connect said connecting circuit withtele phone lines, a loop conductor having a signal controlling relay therein, a transformer haying its secondary winding included in said 7 loop conductor, a source of alternating current connected in circuit with the primary winding of said transformer, and means, operated when said switching apparatus unites with the calling line in response'to a call therefrom, for connecting said loop conductor serially with said connecting circuit, whereby a circuit is completed for current from said secondary winding of said transformer to operate said relay.

30. In a telephone exchange system, the combination with a party telephone line, of a connecting circuit, a connection switch for uniting said connecting circuit with said line. automatic switching apparatus for con necting said connecting circuit with telephone lines, a loopconductor having a source of current and a relay therein, means,

operated when said switching apparatus unites with the calling line, response to a. call therefrom, for momentarily connecting said loop. conductor serially with said connecting circuit, whereby a circuit is completed from said relay and source of current by way'of said conductor, switching appa ratus. calling line and connection switch. a

revertive call signal device operated by said relay when energized, and a locking circuit for said relay completed by itself when: energized. v

31. In telephone exchange system, the combination with aparty telephone lineof a connecting circuit, a connection switch for uniting said connecting circuit with said line. automatic switching apparatus for connecting said connecting circuit with telephone lines, a loop conductor having a source of current and a switching relay therein, means, operated when said switch ing apparatus unites with the calling line in response to a call therefrom, for momentarily connecting said loop conductor serially with said connecting circuit, whereby a circuit is completed for said swit hing relay and source of current by way of said loop conductor, switching apparatus, calling line and connection switch, a locking circuit for said switching relay, a supervisory signal controlling relay, and a circuit for said signal controlling relay having an interrupter therein completed by said switching relay when energized, and a locking circuit forsaid switchingrelay completed by itself when operated.

32. In a telephone exchange system, the combinationwith a party telephone line, of a connecting circuit, a connection switch for imiting said connecting circuit with said line, a t matic switching apparatus for connecting said connecting circuit with telephone llnes, a loop conductor having a source of current and a relay therein, means,

operatedwhen said switching apparatus unites with the callingline in response to a call therefrom for momentarily connecting said loop conductor serially with said connecting circuit, whereby a circuit is coinpleted for said relay and source of current by way of said loop conductor, connecting circuit, switching apparatus and connection switch, supervisory signal controlling relay and circuit for the last mentioned relay having an interrupter therein 00hr pleted by said first mentioned relay when energized, a locking circuit for said first mentioned relay completed by itself when operated, and means controlled by the operator foropening said'locking circuit.

33. Ina telephone exchange system, the combination'with a party telephone line, of a 'springjack connected with said line, a connecting circuit, a plug adapted'to, engage said jack to connect said conngcting circuit with said line, automatic switching appa ratus, a contact arm therefor adapted to be connected with said connecting circuit, said switching apparatus having terminals adapted to be connected with said arm, said switching apparatus being adapted to bring said contact arm into contact with any one of said terminals in response to a call therefor, one of said terminals being connected with saidspringjack, a loop conductor having a source of current and a revertive call signal controlling device included therein, a relay adapted to connect said loop conductor with said connecting circuit, and a circuit.

for said relay adapted to be automatically completed when the contact arm of said switching apparatus engages the terminal of the calledline; whereby when the contact arm of said switchingapparatus engages the terminal of a calling line in response toa call therefrom a circuit is completed for said signal controlling device and a source of current;

I11 a telephone exchange system, the combination with a party telephone line, of a connectingcircuit, a resistance associated with'said connecting circuit arranged to be connected with said line when calling, a

shunt around said resistance and means for momentarily opening said shunt. V

35. In a telephone exchange system, the combination with a party telephone line, of a connecting circuit, a resistance associated with said connecting circuit arranged to be connected to said line when calling, a shunt around said resistance, a supervisory device in series with said resistance and means for momentarily opening said shunt.

36. In a telephone exchange system, the combination with a party telephone line, of

a connecting circuit, test means associated therewith, a resistance associated with said connecting circuit adapted to be connected to the calling line, a. shunt around said resistance and means for opening said shunt I placing a test guard upon saidparty line, a

signal deviceand a circuit for said signal device including said multiple terminals at both ends of said connecting circuit, and means for removing said test guard and closing the circuit of said signal device.

38. In a telephone exchange system, the combination with a party telephone line having multiple terminals, of a connecting circuit adapted to be united therewith, means associated with said connecting circuit for placing a test guard upon said party line, a signal device including a talking conductor. and said multiple terminals at both ends of said connecting circuit, and means for removing said test guard. and closing the circuit of said signal device.

39. In a telephone system, the combination with multi-party line,of a switching circuit extending between two differently located switchingdcvices and adapted to be connected to said line at one of the switching devices when said line is calling and at the other switching device when to be called, and means including a supervising indicator which is also arranged and adapted automatically to indicate. a reverted call at said last named switching device.

40. In a telephone system, the combination with a multi-party line, of a switching circuit extending between two differently located switching devices and adapted to be connected to said line. at one of the switching devices when said line is calling and at the other switching device when to be called, and means including a supervising indicator which is alsoarranged'and adapted to automatically indicate a reverted call at said last named switching device.

11.. In a telephone system, the combination with a multi-party line, of a switching circuit extending between two differently located switch boards and adapted to be connected to said line at one of said switch boards when said line is calling and at the other switch boardwhen to be called, and means including a supervising indicator which is also arranged and adapted automatically to ind cate a reverted call at said last named switch board.

circuit extending between two differently located switch boards and adapted to be connected to said line atone of said switch boards when said line is calling and at the other switch board when to be called, and means including a supervising indicator which is also arranged and adapted to automatically indicate a reverted call at said last named switch board.

&3. In a telephone system, the combinavtion with a line, of a switching circuit, au-

connecting the other end of said switching V circuit with another circuit, and means including a supervising indicator which isv also arranged and adapted automatically to indicate a reverted call.

$5. In a telephone system, the combination with switching circuits extending between two difl'erently located switching de vices and adapted to be connected with a calling line at the one switching device and with a line to be called at the other device of means including an indicator adapted to indicate at one of said devices that a calling line is connected or is going to be connected to said switching circuit, and means including the same indicator as that of the foregoing means for supervision of the call.

2L6. In a telephone system, the combination with a switching circuit extending be-' tween two difi'erently located switching devices and adapted to be connected with a multi-party line at the one device when said line is calling and at the other device when to be called, of means including an indi cater for supervising the call, and means including the same indicator adapted to indicate at one of said devices a reverted call.

$7. In a telephone system, a telephone line, a link circuit, a plug terminal for one end of said link circuit, and an automatic switch for the other end, and a visual sig nal at said link circuit to indicate to the operator thereat when both ends of said link circuit are simultaneously connected to said line 48. In atelephone system, the combination with a telephone line, or" a link circuit, multipled terminals for said line, a plug and an automatic switch for said link circuit, and a visual signal at said link circuit to indicate to the operator thereat when said plug and said automatic switch are simultaneously connected to different ones of said multipled terminals.

4E9. In a telephone exchange system, a line, answering and calling terminals therefor, a connecting circuit, means for extending one end of said circuit to the answering terminal, means for extending the other end of said circuit to the calling terminal, a busy test circuit for said line established upon the extension of said circuit to its answering terminal, a signal, a relay for controlling said circuit, and another relay provided in said connecting circuit for controlling said relay and signal.

In witness whereof, I hereunto subscribe my name this 28th day of January, A. D. 190(.

ALBERT M. BULLARD.

Witnesses:

GEORGE A. HAMILTON, WILLIAM F. LUTTER. 

